The Leica M3 is a 35 mm rangefinder camera by Ernst Leitz GmbH (now Leica Camera AG), introduced in 1954. It was a new starting point for Leitz, which until then had only produced screw-mount Leica cameras that were incremental improvements to its original Leica (Ur-Leica).

The M3 introduced several features to the Leica, among them the combination of viewfinder and rangefinder in one bright window, like on the Contax II, and a bayonet lens mount. It was the most successful model of the M series, with over 220,000 units sold by the time production of the M3 model ended in 1966.

Previous screw mount Leicas used two separate shutter speed dials for slow and fast speeds (the fast speed dial on top of the camera rotated during firing). The M3 combined slower and faster speeds and the dial does not rotate during firing. Supposedly, this reduces vibrations in the camera. Early models used a non-geometrical series of shutter speeds. On later models this became the international standard of 1s to 1/1000s.

Variants and successors

Variants of the M3 were made for specific purposes. The Leica 24x27 was a camera with neither rangefinder nor viewfinder, made for the postal service to photograph electricity meters.

The M3 was supplemented by the M2 with a 0.72× viewfinder more suited to wide angle lenses. The next model was the rangefinder-less M1, intended as an interface with scientific instruments or with a visoflex. With the exception of the larger Leica M5, subsequent Leica M-series cameras have a strong family resemblance to the M3.

In 2002, a miniature replica camera, the Digital Classic Camera Leica M3, was made by Minox (by then bought by Leica).